Electric switch



Jan. 11, 1938. CLARK 2,104,848

ELECTRIC SWITCH Filed Nov. 11, 1935 2 Sheets-Sheet 1 3 T THERMOSTATICSwn'cH a 9e HEATING ELEMENT N LOWER /2 HEATING 1/ ELEMENT 14 5c; 1INVENTOR.

Gaxaoa/v Cum/r BY m, My

ATTORNEYS.

Jan. 11, 1938. "G. H. CLARK 2,104,848

ELECTRIC SWITCH Filed Nov. 11, 1955 2 Sheets-Sheet 2 I F/ci 5 9 TINVENTOR. Gofioa/v /z C'ZA/P/r Patented Jan. 11, 1938 UNITED STATESPATENT OFFICE 2,104,848 ELECTRIC swircn'.

Application November 11, 1935, Serial No. 49,242

3 Claims.

This invention relates to improvements in an electric switch havingreference particularly to a thermostatically controlled switch forconnecting and disconnecting the heating coil circuits in a two-coilsystem.

One of the objects of the invention is the provision of an eflicientdouble electric switch adapted to be actuated by a thermostat, particu-'larly a thermostat of the tubular type, so as to close or open twoelectric circuits in succession when the temperature change affects theentire length of the thermostat, and to close or open one of saidcircuits only when the temperature change affects but one portion ofthe; thermostat. Other objects and features of novelty will appear as Iproceed with the description of that embodiment of the invention which,for the purposes of the present application, I have illustrated in theaccompanying drawings, in which Fig. 1 is an elevational view, partlybroken away and partly in section, showing a water tank with myelectrical heating means installed therein.

Fig. 2 is a diagram of the electric circuits.

Fig. 3 is a plan view of the double switch which .I employ in connectionwith the invention.

Fig. 4 is a side view of the same.

Fig. 5 is a transverse sectional view taken substantially on the line5-5 of Fig. 4 showing the switch in position to connect the lowerheating coil with its energizing circuit.

Fig. 6 is an end view' of the switch.

Fig. 7 is a longitudinal sectional view taken substantially on the line1-1 of Fig. 3.

Fig. 8 is a bottom plan view taken substantially on the line 8--8 ofFig. 7, and

Fig. 9 is a detail view of one of the snap levers of the switch.

In Fig. 1 of the drawings there is illustrated a metallic water tank In,preferably in the-form of a vertical cylinder, which is surrounded by acylindrical metallic casing H, spaced from the tank [9, with suitableinsulation l2 interposed between the tank and the casing.

draw-off connection. Cold water is admitted to the tank l0 through anintake pipe l4 located near the bottom of the tank, while at the top ofthe tank there is a hot water delivery pipe l5. Inthe upper end of thetank 10 there is a central opening i6 in which there is mounted andwelded a collar ii that forms a seat for metal plate l8. A gasket i9 isplaced in the joint between this collar and plate, and the latter isfastened down by a series of studs 20.

5 On the. top of the casing N there is a flanged I3 is a valved metalcover 2| which has a circular'opening in the middle thereof. The inneredge of the cover 2| meets a cylindrical, preferably non-metallic,member 22 that surrounds the collar I1 and serves to confine that partof the insulation I2 5 which overlies the top of the tank 10. 23 is ametal disk with a depending annular rib 24 which extends down into thecentral opening in the cover 2!. The disk 23 is held in place by nuts onthe upper ends of studs 25 which extend up- 10 wardly from the plate illin which they are anchored. Finally, above the disk 23 there is ametallic cap 26 containing insulation 21 and having a bottom rim bymeans of which the cap is secured onto cover 2|.

The heating unit depends from and is supported by the plate E8, thelatter serving also as a closure for the tank. In the present instancethe heating unit is shown as comprising a tube 28,

preferably of copper, having a water-tight connection with theplate l8and having a cap 29 at its lower end joined to the tube by a water-tightconnection. Within the tube there is an upper heating coil 30 and alower heating coil 3|, with electrical connections extending upwardly tothe 25 top of the tube and into the space above plate l8.

The tube 28 is preferably located axially of the tank, that being themost efficient position for the heating coils. Alongside the tube 28,but spaced therefrom to permit free circulation of 30 water, there is athermostat'32. While in some aspects of the invention the particularcharacter of the thermostat is not of importanca'l prefer to utilize oneof the type illustrated which consists of an outer tubular member 33(see Fig. '7) 35 formed of metal having a high coefficient of expansion,and an inner rod 34 formed of metal having a low coeilicient ofexpansion. The tube 33 is preferably threaded into an opening in theplate l8, and the rod 34 projects upwardly through 40 and beyond thatopening. The tube 33 and rod 34 are secured together at their lowerends. The thermostat is guided near its lower end in a bracket 35 whichhas a circular opening'therein to receive the thermostat loosely. Theguide 45 bracket 35 serves to steady the/thermostat 32, and isespecially useful on that account during transportation of the tank. Itwill be apparent that when the temperature of the water in the tank [0rises the tube 33 will expand lengthwise, 50 causing the upper end ofthe rod 34 to descend, while cold water entering the tank will con tractthe tube 33, thereby causing the rod 34 to rise. 7

It will be noted that the cold water intake pipe l4 terminatessubstantially beneath the lower end of thermostat 32, so that theintroduction of cold water into the tank, as hot water is drawn out,affects the thermostat almost immediately.

Near the top of the tank outside the casing I I there is an electricjunction box 85, from which conductors 31 and 38 extend inwardly to thecontrol switch which is mounted on the plate l8 and which will now bedescribed by reference to Figs. 3 to 8 inclusive in connection with thewiring diagram of Fig. 2.

The switch comprises a metallic frame member which consists of a base88, an upright 48, and a shelf 4|, all integral. In the base there maybe formed a pair of holes 42 for the reception of fastenings by means ofwhich the switch is secured to the plate I8. The upright 48 about midwayof its height is deformed to provide V-groove 43 which serves as afulcrum for one end of an angular lever 44 that may be termed theoperating lever. This lever has a knife edge at its inner end that seatsin the V-groove 48. In the lever 44, spaced a short distance from itsfulcrum, there is a threaded opening in which is received the threadedlower extremity of an adjusting post 45. This post has a socket in itslower end into which the upper extremity of thermostat rod 84 extends.The post 45 projects through a slot 48 in the shelf 4| and through asimilar slot in a plate 41 which is secured to the upper surface ofshelf 4| by a pair of shouldered studs 48, which have the additionalfunction of stops for limiting the motion of a pointer 48 that ismounted on the upper end of the post. The pointer 48 also serves as aconvenient means for grasping the post 45 in order to rotate it. It willbe apparent that when the post 45 is turned down, the effective point ofcontact between the lever 44 and the rod 84 is lowered, while theturning of the post 45 in the opposite direction raises the effectivepointof contact between the lever and the rod 34. In order to hold thelever 44 firmly against the rod 84 I provide a coil spring 50, the upperend of which engages the shelf 4|, and the lower end of which engages awasher 5| resting upon lever 44 surrounding the post 45.

On the outer extremity of lever 44 I mount, by means of screws 52 and58, a triangular block 54 of insulating material, and in this block oneither side of the lever holes are provided through which threaded pins55 and 58 extend. On the upper ends of these pins there are nuts 51, bymeans of which the height of the pins may be ad justed. In practice theyare adjusted to different heights, as indicated in Fig. 6, for a purposewhich will presently appear.

A block of insulation 58 is secured to the base 88 by screws 58. On theinner ends of this block there are mounted two sheet metal conductorbrackets and GI which are O-shaped in vertical section with their opensides facing each other. These brackets are held in place partly by twoscrews 62 and 53, and partly by shouldered insulation bushings 84 andthat are held in position by bolts 88 and 81, the upper ends of whichare provided with silver contact buttons 88 and 89 respectively. Contactbuttons 18 and H are secured to the under sides of the top portions ofthe brackets 68 and 8|. From the lower arm of the bracket 8| thereextends laterally an inz'tegral lip 12, in which is mounted a screw 18for securing a wire conductor. 0n the opposite end of the block 58 thereare mounted two separated metal plates 14 and I5. Above these platesthere are thin spring metal plates 18 and. 11.

Sheet metal brackets 78 and 18 rest upon the plates 18 and I1respectively. The parts 14, I8 and 18 are fastened together and to theblock 58 by means of screws 88 and 8|. Similar fastenings for the partsl5, l1 and 18 are used, but not separately illustrated herein. Theupright portions of the brackets 18 and 18 are bifurcated, and each ofthe bifurcations is deformed to provide a V-groove 82, all four of thesegrooves being in alignment. The thin metal plates 18 and 11 constitutethe anchoring portions of two double leaf springs 88 and 84 which arecurved upwardly and forwardly and have their forward portions secured tothe upper sides of a pair of snap levers 85 and 88 respectively. Therear ends of these levers are bifurcated, as will appear particularlyfrom Fig. 9, and the bifurcations are received in the V- grooves 82.They are held against sidewise movement largely by the springs 88 and84, which are secured to the levers not only at the forward end of thelatter but also at points near the rear ends of the bifurcations. Coilsprings 81 and 88 are positioned in the bifurcations of the levers 85and 88 respectively and extend between the bifurcations of the brackets18 and 18, these springs having hooked forward ends that are received inholes in the levers and hooked rear ends that embrace reduced diameterportions on the lower ends of pins 55 and 58. At the forward ends of thelevers there are double contact buttons 88 and 88 electrically andmechanically joined to the levers and to the leaf springs, andpresenting good contact surfaces both above and beneath the levers.Integral lips 8| and 82 extend laterally from the plates I4 and 15respectively, and have screws 88 and 84 respectively mounted therein, bymeans of which wire conductors may be secured, the current being carriedthrough the leaf springs 88 and 84 to the levers 85 and 88 and thecontact buttons 88 and 88.

In the under side of the insulation block 58 a diagonal groove is formedin which is positioned a metallic shunt strip or bar 88, which issecured .at its ends to the screw 82 and the bolt 81.

The rear ends of the coil springs 81 and 88 are positioned near theheight of the fulcrums of levers 85 and 85. When the lever 44 is loweredby the expansion of thermostat tube 88, the rear ends of the springs 81and 88 are lowered and the forward extremities of the levers 85 and 88are drawn down upon their abutments or contact plates 68 and 88. As thetube 88 contracts how ever, raising the rod 84 and swinging theoperating lever 44 upward, the rear ends of the springs 81 and 88 passover or above the fulcrums of the levers 85 and 88, thereby snappingthose levers into their upper positions, where they contact with thecontact buttons 18 and I I. In the usual adjustment of the pins 55 and88 this snap-over.

of the levers 85 and "takes place at different times in the movement ofthe thermostat. How ever, if it should be desired to make the two leversmove simultaneously, this can be accomplished by positioning them at thesame height in the insulation block 54;

Referring to Fig. 2, it will be seen that upper heating coil 88 isconnected to conductor bracket 8| and contact button 'H through the lipI8 on the bracket, while the oppomte end of the coil is connected by aconductor 85 with line wire 81'. Lip 82 is connected with line wire 88,while lip 8| is connected by a conductor 88 with one end of the lowerheating coil 8|, the opposite end of I Assuming that the tank is filledwith cold water,

operating lever 44 of the switch will be in its raised position, due tothe contraction of thermostat tube 33. Both snap levers and 86 will alsobe in their raised positions, or as indicated in Fig. 2, Where thebuttons 89 and 90 are shown in contact with the buttons 10 and H.Current will then flow through the upper heating coil 30. This willcontinue until the heated water in the upper part of the tank has causedthe t be 33 to expand sufiiciently to lower the operating lever 44 tosuch an extent as to snap lever 86 to its lower position, when thecontact 90 will engage button 69 on bolt 61. The circuit through coil 30will thereby be broken, and a circuit will be set up from line wire 38through snap lever 86 to contact 69 and bolt 61, thence through shuntbar to screw 62, bracket 60 and contact button 10. Lever I5 being stillin its upper position, current passes from button 10 to button 89 on thelever and thence through the. lever and spring 83 to plate 14 and lip 9I, through conductor 96 to lower heating coil 3|, and through conductor91 to line wire 31. The heating of the water in the lower part of thetank then continues until a predetermined temperature is reached, whenthe thermostat acts to lower lever 44 sufllciently to snap lever 85 toits lower position where it contacts with button 66, which is merely aninsulated abutment. The circuit through the lower coil is thus broken.

In the event thatonly a small quantity of hot water is drawn from thetank, and a corresponding quantity of cold water is admitted beneath thethermostat, the latter will then raise the lever 44 a short distancesuflicient to again snap lever 85 upwardly, returning it to contact withbutton 10. The circuit through lower heating coil 3| will thereforeagain be set up until the temperature is raised to the extent demandedby the thermostat, after which the'latter will act to disconnect coil3I, as will be apparent.

Should the quantity of hot water withdrawn be considerable, the firsteffect will be to energize lower coil 3!, but this effect will be onlytemporary or until the cold water entering the tank has reducedthetemperature sufliciently to snap lever 86 also to its upper position,when coil 3| will be cut out and coil 30 will be cut in, whereupon theoperation will be the same as above described for the condition wherethe current is turned on to heat a tank full of water.

In the ioreSOin description I have necessarily gone somewhat into detailin order to explain fully the particular embodiments of the inventionherein illustrated, but I desire it to be understood that such detaileddisclosures are not to be construed as amounting to limitations, exceptas they may be included in the appended claims.

Having thus described my invention, I claim:

1. In automatic control apparatus for a plurality of heating coils, alever, thermostatic means for swinging the lever in response totemperature changes, a conductor lever for each heating coil, adjustablespring supports carried by said first named lever one for each of saidcoils, springs attached at their ends to said supports and saidconductor levers adapted to hold said conductor levers in either on oroff position, whereby the diflerent adjustments of said spring supportswill cause said conductor levers to snap from one extreme position tothe other extreme position either simultaneously or one at a time atpredetermined points in a given movement of the thermostat in responseto rising or falling temperature.

2. In an automatic control apparatus for a pair of heating coils, twoconductor levers pivotally mounted with their pivots in alignment, twospring supports movable transversely across the line of said pivots, twosprings each attached at one end to one of said supports and at theother end to one of said levers, whereby the springs are adapted to holdthe levers in either of two extreme positions, an element movabletransversely of said line of pivots, said element being adapted to be somoved by thermostatic means in response to temperature changes, andmeans for adjustably connecting said supports to said element, wherebythe conductor levers will snap from one extreme position to the otherone at a time at predetermined points in a .given movement of thethermostat in one direction.

3. In apparatus of the class described, means for moving an electriccontact from operative to inoperative position and vice versa,comprising a lever, a coil spring on one side of said lever tending tohold it against movement in one direction, and a shaft extending throughsaid spring threadably mounted in said lever and extending through thelever to form an abutment on the side opposite the spring for engagementwith any suitable lever swinging element, whereby rotation of the shaftvaries the adjustment of said abutment.

GORDON Hi CLARK.

